#include<stdio.h> 
int main()
{
	int x;
	scanf("%d",&x);
	int n=x/10;
	switch(n)
	{
		case 0: case 1: case 2: case 3: case 4: case 5: printf("E"); break;
		case 6: printf("D"); break;
		case 7: printf("C"); break;
		case 8: printf("B"); break;
		case 9: case 10: printf("A"); break;
	}
	return 0;
}
